Request to enable gd extension

[victormacko]

Thanks in advance for all the work being put into Bref -- it's really appreciated!
I asked the question about GD on slack a few weeks back but thought i'd put it here as well in the mean-time in the hope it might make it into the standard run-times in future.

Currently there's no way of using image-functions (eg. resizing images / cropping / etc) in bref -- i'm looking at processing images uploaded to S3 automatically (via messages from SNS).
From memory it was mentioned that the overhead of the extension is roughly 630kb.

Thanks in advance for considering it :)

[victormacko]

Just on this -- I've spent a bunch of time compiling GD and run into a bunch of things (had to stop because of PHP version inconsistencies), but looks like it's definitely possible to have standalone layer with GD and it's associated libraries, separate from the standard Bref layer, and without having to alter anything in the existing bref layer (i'm yet to test it 100%, but it's certainly looking possible)

I've compiled the GD extension as a bundle with the separate libraries it needs, and uploaded it as an additional layer after the Bref layer in cloud-formation/serverless.
I then enabled the extension using a .ini file in the deployed code (/php/conf.d/php.ini).

[mnapoli]

Done in #396